Sources of Electricity

1
Sources of Electricity

• Electronics 1
• CVSD

2
Resistance

• A measure of the opposition to the flow of
  electrons through a material
• Unit of Measurement
• Ohm (O)
• Symbol
• R

3
Voltage

• A measure of the Electromotive Force that pushes
  electrons through a circuit (Potential
  Difference)
• Unit of Measurement
• Volt (V)
• Symbol
• E

4
Current

• A measure of the Intensity or total amount of
  electrons flowing in a circuit in a given unit of
  time
• Unit of Measurement
• Ampere (A)
• Symbol
• I

5
Power

• A measurement of the rate of consuming energy,
  transferring energy, or doing work
• Unit of Measurement
• Watt (W)
• Symbol
• P

6
Six Sources of Electricity

• Chemical
• Magnetic
• Friction
• Pressure
• Heat
• Light

7
Chemical

• Uses unlike materials (electrodes) in a solution
  (electrolyte) to form a voltaic cell
• Cell Two electrodes with an
  electrolyte in between
• Battery Multiple cells strung
  together in series /or
  parallel circuits
• Primary cell cannot be recharged
• Secondary cell can be recharged
• Cells can be wet or dry
  
  (refers to electrolyte)

8
Magnetic

• Uses a conductor armature passing through a
  magnetic field (lines of flux)
• As the conductor cuts through the lines of
  flux, a voltage is produced (electrons attracted
  to or repelled by the field)
• Used in generators
  to convert
  mechanical
  energy into
  
  electrical energy
• Amount of current
  produced
  depends on speed
  of armature of coils in the armature

9
Friction

• Electrical charge can be produced from rubbing
  certain unlike materials together (electrons
  transfer from one of the materials to the other)
• Called static electricity
• The release of this static charge
  results in a
  static shock (lightning,
  when you shock yourself
  
  on metal, etc)
• Friction between the touching
  surfaces often causes
  heat
  (helps transfer electrons)

10
Pressure

• Some materials will transfer an external pressure
  to their internal atoms, which drives their
  electrons out of orbit (causing an electric
  charge)
• Most common material crystals
• Used in microphones and
  phonograph pickups
• Convert mechanical energy
  into
  electrical energy

11
Heat

• Two unlike pieces of metal joined together
  produce electricity when heated
• Called a thermocouple
• Current depends on the amount of heat types of
  metals used
• Converts thermal energy into electrical energy
• Used in conjunction with a ammeter to make a
  pyrometer (measures high temperatures)

12
Light

• When light hits certain materials it releases
  electrons, causing an electric charge.
• Main principle behind solar
  cells (photo voltaic cell)
• Solar cells are made of
  silicon, when
  light waves
  hit the silicon they
  release
  electrons
• Convert light energy into
  electrical energy
• Amount of current depends on amount of light

13
Review

• Voltage is
• Current is
• Resistance is
• Power is
• What are the six sources of electricity?
• List the principle parts of a voltaic cell
• Lightning comes from which source?
• What is the difference between a primary and
  secondary cell?